Impact of 2 days of staging at 2500–4300 m on sleep quality and quantity following subsequent exposure to 4300 m

The impact of 2 days of staging at 2500–4300 m on sleep quality and quantity following subsequent exposure to 4300 m was determined. Forty‐eight unacclimatized men and women were randomly assigned to stage for 2 days at one of four altitudes (2500, 3000, 3500, or 4300 m) prior to assessment on the summit of Pikes Peak (4300 m) for 2 days. Volunteers slept for one night at sea level (SL), two nights at respective staging altitudes, and two nights at Pikes Peak. Each wore a pulse oximeter to measure sleep arterial oxygen saturation (sSpO 2 , %) and number of desaturations (DeSHr, events/hr) and a wrist motion detector to estimate sleep awakenings (Awak, awakes/hr) and sleep efficiency (Eff, %). Acute mountain sickness (AMS) was assessed using the Environmental Symptoms Questionnaire and daytime SpO 2 was assessed after AMS measurements. The mean of all variables for both staging days (STG) and Pikes Peak days (PP) was calculated. The sSpO 2 and daytime SpO 2 decreased ( p  < 0.05) from SL during STG in all groups in a dose‐dependent manner. During STG, DeSHr were higher ( p  < 0.05), Eff was lower ( p  < 0.05), and AMS symptoms were higher ( p  < 0.05) in the 3500 and 4300 m groups compared to the 2500 and 3000 m groups while Awak did not differ ( p  > 0.05) between groups. At PP, the sSpO 2 , DeSHr, Awak, and Eff were similar among all groups but the 2500 m group had greater AMS symptoms ( p  < 0.05) than the other groups. Two days of staging at 2500–4300 m induced a similar degree of sleep acclimatization during subsequent ascent to 4300 m but the 2500 m group was not protected against AMS at 4300 m.